<p>Bucketing, also known as fixed cells, is a data structure that is especially suitable for queries that cover small windows. However, this technique is not efficient if objects are long and narrow, such as wires. Also, as more objects are added, the efficiency of the query process may suffer. The authors describe a dynamic bucketing structure that maintains a two-level director structure and uses a directory doubting and merging technique called extendible hashing. This technique allows directories to expand without sacrificing performance as more objects are inserted into the structure. They report the results of tests comparing the performance of dynamic bucketing with the performance of the quad-tree algorithms.</p>